Sprains and other injuries of the anterior cruciate ligament (ACL) of the human knee are painful, debilitating, and expensive and time consuming to repair and rehabilitate. In skiing, the incidence of ACL injury began to rise in the late 1970s to become the sport's most common serious injury by the late 1980s. Since the early to mid 1990s the risk of sustaining this injury has stabilized and then declined modestly. However, at 15% to 20% of all ski-related injuries, it still remains the most common injury, with more than 20,000 per year in the U.S. alone. From 1983 on, changes in the incidence of ACL injury have been tracked by a series of “Trends” papers published as Special Technical Publications (STPs) by the American Society for Testing and Materials (ASTM).
In October, 1995, the American Journal of Sports Medicine published a paper titled “A Method To Help Reduce The Risk Of Serious Knee Sprains Incurred In Alpine Skiing.” The paper documented the results of a training program for on-slope ski-area employees at 20 ski areas in the U.S. and compared injury rates for the group with both a historical control group (the same ski areas for the two prior seasons) and an ad hoc control group of 20 ski areas that had not yet joined the training regime. The training involved a highly structured, video-based discussion format. Actual footage of ACL injuries was used to create a kinesthetic awareness of the events leading to the most common types of ACL injury. The program reported a 62% reduction in ACL injuries overall, and for ski patrollers, the highest risk subgroup, the reduction was 76%. This program identified the “phantom foot” scenario as the most likely mechanism of ACL injury. In this scenario the skier is off-balance to the rear with most of the weight on the downhill (outside) ski.
In later studies published in ASTM STPs, it was shown that the equipment associated with ACL injuries was comparable in quality and overall release performance to the equipment of the general population at risk but superior in every quality to equipment associated with sprains and fractures below the knee. These studies show that contemporary ski bindings, regardless of their condition, are not capable of reducing the risk of ACL injuries.